Members of the genera Mycoplasma (a genus requiring sterols) and Acholeplasma (a genus capable of growth without sterols), hereinafter referred to as mycoplasma, are the smallest (0.2 to 2 .mu.m in diameter (Hay, R. J. et al., (1989) Nature 339:4)), and the simplest free-living parasitic organisms known. Mycoplasmas differ from bacteria in lacking cell walls and possess the smallest recorded genome in living cells, from 0.5.times.10.sup.9 to 1.0.times.10.sup.9 Da (Lo, S.-C et al., (1991) Science 251:1074-1076; and Razin, S., (1985) Microbiol. Revs. 49:419-455). Mycoplasma are known to infect both animals and plants causing, or being implicated in the cause of, a variety of diseases (Brown, T. et al., (1970) Trans. Amer. Clin. and Climatol. Assn. 82:227-247; Brown, T. et al., (1973) Internal Congress On Rheumstology, Vol. XIII, Amsterdam: Elsevier/Excerpta Medica, p. 172 (International congress series No. 299); Chowdhury, M. I. H. et al., (1990) Biochem. Biophys. Res. Comm. 170:1385-1370; Clark, H. W., (1991) Amer. J. Primatol. 24:235-243; Kundsin, R. B. et al., (1981) Science 213:474-478; Lemsitre, M. et al. (199) Res. Virol. 141:5-16; LeMaitre, M. et al., (1992) Inf. and Immun. 600:742-748; Lo, S-C. et al., (1989) Am. J. Trop. Med. Hyg. 41:586-600; Lo, S.-C. et al., (1991) Science 251:1074-1076; Saillard, C. et al., (1990)Res. Virol. 141:385-395; and Wright, K., (1990) Science (Research News) 248:682-683). Therefore, the of the mechanism of the activity of mycoplasma is important.
Many species of mycoplasmas can be grown axenically in broth media containing undefined, exotic additives. However, the quantitation of broth-grown mycoplasmas has been a problem. Unlike broth cultures of larger bacteria, in which turbidity parallels growth and which, therefore, can be quantified turbidimetrically, cultures of many mycoplasmas have reached peak growth before turbidity is apparent. Where pH changes occur in mycoplasmal cultures, a color change in the media is often used to indicate peak growth. However, not all mycoplasmas cause a medium color change and if so, such a change may not coincide with peak growth. Colonial growth on agar is one method of quantitation which has the drawback that the data is always obtained retrospectively, as the original culture is gone by the time colonies are of a size sufficient for quantitation. These difficulties have hampered the standardization of cultures within and between laboratories and the development of new and defined media for cultivation. Moreover, the evaluation of antimycoplasmal agents and the general understanding of mycoplasmal growth characteristics has been hindered due to a lack of an accurate real time quantitative assay. The necessity of using complex and undefined media to grow mycoplasmas precludes any rapid development of mutants important in analysis of mycoplasmal pathogenesis. An assay for the quantitation of mycoplasmal growth and the study of antimycoplasmal agents would be beneficial.